


Divinity Disguised

by Adel Mortescryche (Mortescryche)



Category: Hades (Video Game 2018), Katekyou Hitman Reborn!
Genre: Alternate Universe - Canon Divergence, Crossover, Crossovers & Fandom Fusions, Don't copy to another site, Dysfunctional Family, Family, Family Feels, Friendship, Gen, Old Gods, You choose your own family, khrrarepairweek
Language: English
Status: Completed
Published: 2020-06-22
Updated: 2020-06-22
Packaged: 2021-03-04 02:29:12
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,984
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24866092
Author URL: https://archiveofourown.org/users/Mortescryche/pseuds/Adel%20Mortescryche
Summary: "Zag," Tsuna mumbled, reaching up to snag an arm around Zagreus' neck, hugging him as tightly as he could in spite of the awkward angle.The older man laughed, voice quiet in the night, wrapping an arm around Tsuna to hug him back just as tightly."What's this I hear about the mafia recruiting you, little brother?" He asked, sounding distinctly amused.Or, that one in which Zagreus was simply minding his own business, when along came along this tiny kid who got lost in the streets and needed help getting back home.Alternatively, the tale of how Tsuna managed to find his very own older brother. Who cares if he was a little more divine than previously expected.
Relationships: Reborn & Zagreus, Sawada Tsunayoshi & Zagreus, Zagreus & Olympian Gods
Comments: 25
Kudos: 486
Collections: KHR Rare Pair Week 2020





	Divinity Disguised

**Author's Note:**

> _"“Every man is a divinity in disguise, a god playing the fool."_ \- Ralph Waldo Emerson.

Tsuna blinked awake slowly, turning over in bed to meet the hand gently jostling his shoulder.

The mismatched gaze peering down at him in the dark was a familiar sight. The man bent over him was heavily shadowed, but there was no one else it could really be, not when his right eye glowed red.

"Zag," Tsuna mumbled, reaching up to snag an arm around Zagreus' neck, hugging him as tightly as he could in spite of the awkward angle.

The older man laughed, voice quiet in the night, wrapping an arm around Tsuna to hug him back just as tightly.

"What's this I hear about the mafia recruiting you, little brother?" He asked, sounding distinctly amused.

"Ugh, don't remind me."

Tsuna grumbled under his breath, letting go and shifting aside, just enough for Zagreus to perch on the edge of his bed. He still looked distinctly amused, but Tsuna wasn't mistaking that for a lack of concern. He _knew_ how the older man could get, if it was something that concerned Tsuna's safety. 

"Did you just get back from Olympus?"

Zagreus lifted a single shoulder, looking disinterested. It made Tsuna bite his lip in concern, but he made no move to actually voice it, not when the subject of his Godly Grandmother and his Father were still such sore subjects for the older man.

"I didn't tell Reborn about you, but who knows if Mom brought it up. She and Reborn have been having long chats over coffee every morning." Tsuna said, changing the subject abruptly. It made Zagreus smile, but his brother and guardian didn't say anything, simply nodding and waiting for Tsuna to continue.

Venting about Reborn, and Iemitsu, and the whole darned situation with the Vongola was _cathartic._ Tsuna had been missing his brother terribly the entire time he'd had to deal with Reborn's violent teaching methods. He knew Zagreus wouldn't have had much to say on the violence, not when _Zagreus'_ idea of training and friendship were in the same category as Reborn's. But the fact that Iemitsu and the Kyuudaime of the Vongola had decided, arbitrarily, that Tsuna would be the next Don of the Vongola and had to be trained for that? Oh, Tsuna knew his brother would take his side on that front.

Zag _hated_ it when someone else tried to force their opinions or expectation on him - it was why Tsuna had bonded so easily with him, back when they'd first met. Zagreus had been kicking back the cafe he'd closed for the night, easily strumming the strings of a guitar, and Tsuna had been the kid lost in the streets at night, unable to figure out how to get back to his parents.

Tsuna still had nightmares about getting lost on a moonless night, about his hand slipping from his mother's in the middle of a crowd, and then wandering until all the shops had closed. He'd followed the sound of strings to the cafe. Zag had heard him crying at the door, and had set aside his guitar out of pure curiosity, coming outside to meet him face to face.

The next thing Tsuna had known, the world had blown open in front of his eyes. And the concerned, dark haired man standing in the cafe doorway had gone from looking like a unfamiliar foreigner to something Other.

"Tsuna?" 

Tsuna blinked, and smiled awkwardly.

"Sorry. Remembering something from long ago."

Zag smiled softly, reaching out to ruffle Tsuna's hair.

"I can relate to that, kiddo. I'd been trading shots with Dionysus a couple of days ago, and _man_ did that unearth a lot of old memories."

That made Tsuna _laugh._ Zag's stories of his many cousins were always worth listening to. It made Tsuna wish he had siblings of his own, not to mention cousins, at times. But both his parents were single children, and had never felt the need to have another child. His mother had laughed, claiming that Tsuna had been all she wanted, but on the darker nights when Zag wasn't in Namimori, especially after a long day at school, Tsuna couldn't help but think the real answer was that his mother simply couldn't handle another child on her own.

"Go back to sleep, brother," Zag murmured quietly. "It seems like you've had a long day."

Tsuna blinked at him in surprise, and couldn't help the fond smile that tugged at his lips, feeling like the open hollow in his chest was being filled back in.

"That obvious, is it."

"Yes."

The blunt response had Tsuna snickering under his breath, but he acquiesced easily enough, curling up under his sheets, and smiling a little wider when Zagreus neatly tucked the sheets around him.

"Sleep well. I'll be here in the morning."

Tsuna hummed sleepily in response, feeling his eyelids grow heavier. There was a tell-tale tingle in the air that told him Zag had cheated and used magic, but Tsuna couldn't hold it against him.

"Will you stay over?"

Zagreus smiled wryly at that, and ruffled his hair again, before standing up.

"I doubt it. But I'll be there when you wake up."

Tsuna _smiled_ , feeling the hollow in his chest fill to bursting. It made Zagreus chuckle quietly - and the sound of his older brother's laughter was the last thing Tsuna heard before he gave into the siren song of sleep once more.

*

Reborn was used to being the first up in the morning, even before Nana was awake, and well before his new student started shifting in bed. It made him relieved to have been offered the guest room in the Sawada household. For all that he'd been mentally prepared to bunk with his student if he had to, all the better to train the boy into some good habits, having his own space to work in and not play the odd, idiosyncratic foreign child had been a relief.

It was much to his surprise that he found he _wasn't_ the first person awake in the house, for once. His trip to the kitchen to get the coffee pot running before doing anything else found him face to face with a stranger busy doing exactly what he'd planned to do.

The man by the kitchen counter glanced up the moment Reborn set foot through the doorway - a glimpse of enough spatial awareness to have Reborn's hackles rise. Not that he made any outward sign of it, of course. He wasn't an _amateur._

Whoever the man was, he wasn't Japanese. Not by race. Pale, faintly olive tinted skin, and a well-defined nose and jawline, coupled with dark hair and sharp, tumultuous green eyes, putting together a picture that spoke to Reborn more of his own homeland than anything that he was expecting to see in the Sawada household any time soon.

"You'd be the tutor, then," the man commented blandly, turning back to the coffee he'd been in the process of pouring into a mug.

"Ciaossu," Reborn offered readily, hopping up onto the dining table. "I'm Reborn."

"Zagreus," was the answer offered in turn. "It seems you've been rather… singular in training my little brother whilst I was away on family business."

Reborn stiffened immediately, fingers twitching for a gun. Or any other weapon that was more readily available. The words were candid, sure, as was the tone, but something was Off. He could sense it in the air, in his very blood.

The last Reborn had felt anything even remotely similar to this man, he'd been led up to a mountain top alongside his fellow Arcobaleno by Checkerface, to be changed inside and out.

Zagreus glanced over his right shoulder, the one eye that Reborn could see through his messy hair glinting blood red, uncannily so, before it went back to looking green.

"Coffee?" He asked mildly, and Reborn's fingers clenched down on the edges of the table top he was seated on.

"Much obliged. Maman isn't usually up this early."

Zagreus laughed at that easily enough, preparing another mug for him, making no move to search for something more child sized. Reborn took another, slow, breath. And wondered if he could get away with going for the knife in his ankle sheath before the man would react.

A coffee mug was set down beside him before he could do anything of the sort. Reborn looked down at the mug, and then up at the man standing before him, eyes going narrow in his head.

Zagreus smiled at him pleasantly, tugged out a chair for himself, sat down and took a deep draught of his coffee before speaking again.

"I trust I won't have to mince words?"

"No." Reborn responded, pulling his legs up into a more comfortable position, and reaching for his own mug. "I'll appreciate it if you can tell me how you managed to stay unnoticed until now, however."

Zagreus snorted at that, the corner of his lips canting up into a roguish smirk.

"What, like it's hard? And anyway, none of them were on the lookout for… someone like me."

Reborn suspected that the other man wanted to use another word in place of someone. Potentially… some _thing._

He pursed his lips, and took a sip of the coffee to give himself something to do. The action had Zagreus' smile widening into an expression that was far toothier before he went back to looking as mild as milk.

"...how long have you been in touch with the Sawada household?"

Surely the lack of discursiveness would make the man speak more freely. Or so Reborn hoped. From the side-eye his words netted him, it didn't seem likely.

Zagreus gave in easily enough, though Reborn could _see_ the amusement in his eyes. And it made Reborn's fingers itch for his gun all over again.

"Since Tsuna was a toddler, I suppose. He got lost, and found himself at my doorstep. I saw no reason to turn a crying child back out into the dark night without making at least a token attempt to locate his parents."

...meaning, Zagreus had known Tsuna for long enough that he'd potentially become a part of his life the way a blood sibling or parent would. Oh, Reborn would have _words_ with Iemitsu - and with Timoteo as well. Missing a link like this was what got undercover agents killed before they could find anything useful.

Zagreus smiled charmingly at him, and Reborn smiled back, lifting his mug to hide the hard edge of the expression in the coffee within.

This was the tableau that Tsuna walked in on, once he was awake enough to hunt for breakfast. He took one look at his older brother and tutor smiling daggers at each other, and all but crabwalked back out.

*

Listening to the small, mousy haired child crying into the phone, presumably speaking with his parents, Zagreus sighed tiredly, running a hand down his face in sheer, bewildered exhaustion.

"You've really done it this time, cuz," Hermes commented from where he was leaning against the wall at Zagreus' side, smiling in unholy amusement.

" _Please_ don't remind me, divine cousin." Zagreus muttered back, making the other god _laugh,_ the sound as gleeful with delight as it had ever been.

"Oh, the look on Uncle Hades' face if he finds out you somehow tied your divinity to a _mortal._ What was it those Precursors called them again? Flames of the Dying Will?"

Zagreus peered up at Hermes from between his fingers, eyes narrowed, and was met with a cheeky grin in return.

"Well, you're lucky I managed to find the kid's parents. Iris probably would've gossiped a lot more about it," he commented, as if Hermes himself wouldn't carry tales to the rest of their cousins as soon as his feet could carry him to them.

Zagreus had to stifle the groan he wanted to give, far too tempted by the thought of banging his head against a wall. Or, potentially, jumping off of a building, or walking into the path of a moving train. Getting destroyed down to energy waves and godly blood before being put back together had a nice way of clearing the head like nothing else.

He controlled the urge when he saw the shy glance the child at the phone darted his way, instead tempering his grimace into a smile, if slightly strained.

Hermes _chortled_.

"At least the kid's cute?"

" _Thank_ you, Hermes." Zagreus grumbled, and got a hard pat on the back for his troubles.

At least Zagreus could say, in full faith, that even with all the jokes Hermes was cracking at his expense, he hadn't been expecting what had happened either. Nor had Zagreus himself, when he'd unlocked the café door.

A child crying at his door? Zagreus couldn't ignore that. Not for anything in the world. But nothing could have prepared him for the way his energy _twisted_ when he came face to face with the child, who managed to all but drag Zagreus' divinity out to the forefront in spite of his distress. Or, possibly, because of it.

The child hadn't looked surprised, or scared, even when faced with Zagreus in his true form, with the energies of the Underworld clinging to him like a bloody mantle. Zagreus had seen older humans get reduced to gibbering wretches in the face of true divinity, and yet, here was a child who, when faced with the Unveiled Form of the Son of Hades, had been nothing but grateful to have been heard fairly.

It made something in him ring with a painfully familiar note. Like the pluck of incautious fingers over the strings that made his very being. Looking at the child felt like looking at _himself,_ for all that the child was human, and a toddler besides. 

The touch of a gentle hand on his shoulder made him look up, and pause, when he saw the careful concern in Hermes' eyes. It wasn't like he didn't know his cousin cared, but Hermes was so good at hiding any real emotion from others. It made Zagreus smile awkwardly, unable to help himself.

"Thank you for coming on such short notice, cousin."

Hermes scoffed, squeezing his shoulder just once, before letting go.

"Hardly short notice when I can be wherever I want whenever I want it, cuz. And this was important enough to let some messages be delegated. Don't hesitate to call on me again if you need me, right?"

"Right." Zagreus nodded firmly in reply.

Hermes grinned again, and waved his fingers in a cheery farewell, before collapsing into light that faded from view. Zagreus rolled his eyes, dramatic as always, was his cousin, and pushed himself back to his feet, making his way to the living room.

The child was just about done with his call. He carefully passed the phone back to Zagreus, who in turn rattled away his address over the line so the boy's parents could actually come collect him.

"They should be here soon," he offered, once he'd actually put the phone back on its hook.

The boy nodded violently at that, looking as though he would tumble forward with the strength of the action.

"Mama said she'd been looking for me! She was really happy." 

Zagreus couldn't help but notice the lack of mention about the boy's father - and the voice on the phone had been female as well. He let it go, though. He didn't want to go looking for trouble where there was none.

"Your flames are really pretty," the boy offered shyly, making Zagreus still.

"...so you _can_ see them, then." He murmured, and the child flushed, looking down and twiddling with the hem of his shirt.

Flames of Dying Will, Hermes had called them. Surely there had to be some reason a mortal was able to see his divinity. Zagreus found himself sighing, again, and he crouched down, snapping his fingers once to catch the boy's attention.

"It's okay, I'm not angry. Simply surprised. What can you see?"

The boy blinked up at him, and looked down again, tapping his fingers together timidly.

"It's... Red and Orange flames. They're really pretty. Sorry." The boy offered in a small voice. 

Red and Orange, and no doubt some Yellow as well, if the boy watched for long enough. Apparently Hades' Standard wouldn't leave him be even after the untold centuries he'd spent away from the Underworld.

That wasn't the boy's fault, though. So Zagreus gentled his smile, and was rewarded with a tiny quirk of lips in turn.

He would have to keep an eye on the child, no doubt. They were tied together, after all, and Zagreus knew better than to ignore the direction of the Fates.

Time would tell where this would lead. If nothing, he could try to make the child's life more comfortable, and less prone to losing his way.

Zagreus had distanced himself from closer relations for long enough - perhaps this was a sign from his foster sisters to, ah, get with the program. And the signs of the Moirae weren't to be trifled with. Even if they _were_ his much older sisters, looking to keep him in good health. If only to make Nyx happy.

Blood would always hold true, as would Life. Zagreus knew that better than anyone else.

When the child blinked up at him, innocently baffled by the involuntary laughter that was bubbling out of his chest, Zagreus had to grin, charmed in spite of himself.

"What's your name, child. I'm Zagreus."

The child gave him a wide, gap toothed smile, and replied. 

Tsuna. A fitting name for his future. Zagreus would take that luck of that bond and move forward.

And if it turned out that strum of the strings within him had been for a reason, well. Zagreus already knew how to handle fathers who felt the need to dictate the lives of their children.

Practice made perfect.

**Author's Note:**

>  **AN:** Um. Hi? Yes, it's been literal ages. And I'm quite bleary right now, what with it being close to... ugh. 3:30am.  
> I hope everyone's doing well, even under these present conditions. re: the pandemic, Stay Home, Stay Safe. And if you're a part of the BLM movement, please take care, and again, stay safe. Take care of each other. Don't allow yourselves to get hurt.
> 
> Okay, on to the actual story! A friend (volxdosioda) recced _Hades_ to me, and man, it's been a blast all the way through. Such a great game, with fantastic art and characters - Supergiant Games is On Point, as always. And seeing as KHR Rarepair Week 2020 has an Old Gods prompt for Sky Day, well, I couldn't help myself okay.
> 
> I hope you enjoyed reading this short crossover! I certainly enjoyed writing it. Please let me know what you thought in your comments!


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